Impact wrench structure for tightening or loosening rod joints



June 18, 1963 M. A. YOUNG 3,094,021

IMPACT WRENCH STRUCTURE FOR TIGHTENING 0R LOOSENING ROD JOINTS Filed Oct. 26, 1960 IMPACT WRENCH ANVIL MEMBER INVENTOR. Mae/v1.4 14; 96am; BY gay) JIM-4 United States Patent Ofifice 3,094,021 IMPACT WRENCH STRUCTURE FOR TIGHIENING R LOOSENING ROD JOINTS Merrill A. Young, Gates Mills, Ohio, assignor to Curtlss- Wright Corporation, a corporation of Delaware I Filed Oct. 26, 1960, Ser. No. 65,074 6 Claims. (Cl. 81--52.3)

This invention relates to improvements in impact wrench devices and to a novel procedure in connection with screw-thread-coupled members of such character that application of torque applying means to each element of each pair of thread-coupled members is necessary in order to prevent torque applied either to tighten or loosen the threaded joint from being dissipated idly. The essential problem is represented by the equipment and operations involved in making up and breaking out of sucker rods for petroleum pumping in oil wells. Sucker rods in the process of being connected by threaded couplings as usual (and while breaking out) have sufiicient elasticity so that, during torque applying operation of a wrench, unless non-yielding reactance torque is maintained as by a backup wrench or equivalent (some-' times called a snipe) close to the threaded joint involved, the rod will twist and thus idly absorb whatevertorque is applied to the joints. Y

- The most widely used' sucker rods in present day petroleum production are of the double pin type. The -pins are the threaded ends of sucker rods designed to be joined together via internally threaded couplings having appropriate wrench, flats. During make-up, axial shoulders on so called collars at the upset ends of the. rods must be brought into full face abutting contact with the associated coupling end faces so that the metal of the rod and coupling constituting each joint is subjected to a predetermined greater tension than can occur in the well due to suspension of the rod string and/or operation of a pump. Since, under the terrifiic tension forces involved, the threaded pins are normally the most vulnerable portions of the rods, the torquing during makeup either by power or hand wrenches must be reasonably uniform for a particular grade, size, service,; etc; of rod. Power r-od Wrenches are availablein the industry which are supposed to provide means formeasuring or accurately predetermining the make-up torque. In such wrenches the torque is usually determined bythe stall point of the motor mechanism driving the wrench. Therefore important but unnoticeable variations in torque can occur for numerous reasons (power fluid pressure variations, friction in drive train 'etc.). Further such power wrench tools are massive, complicated and, expensive and must be lifted into operating position by power hoist mechanisms, thereby introducing greater hazards to workmen than are presented'by the use of manually operable rod wrench tools. Further, important injury to critical surfaces such as the sucker 'rod wrench faces or flats during application and/or operation of such power units is commonly experienced,isimilarly to the injury likely to be done ,by hammering when using manual wrench devices.

Manually operable sucker rod wrench devices having provision for delivering impacts designed to increase joint making and breaking torque over values that can be applied manually via the wrench handle or handles are already known. One reason such devices have not attained wider recognition in the industry is that although greater torque with a given length of wrench handle can be applied to the joints through use of those devices the actual torque depends upon the person using the wrench with resultant undesired variation in torquing of at least some of the joints during make-up of a com 3,094,021 Patented June 18., 1963 plete string of rods. In the present improvement, indicating one of its objects, applied torque both for rodmake-up and breaking out purposes is accurately predeterminable as governed by design or adjustment of the impact wrench portion; and effectual torque conserving means are applied conveniently without danger of injuring critically important rod surfaces as will be explained. Also, by the use of the improvement, indicating a further object, all reactance torque incident to adequate tightening of sucker rod joints .by utilization of impact is certainto beabsorbed above ground, whereby (assuming a lower end or other portion of the string, as in case of considerable deviation or curving of the drilled hole, is subjected to substantial friction) the rod string already in the well cannot flexibly store torque which can later act to loosen a threaded joint.

The impact wrench portion of the mechanism (as shown herewith somewhat diagrammatically), is as shown herewith by way of example, substantially that disclosed by United States patent of Oscar J. Swenson, 2,954,714, issued October 4, 1960. i

In the accompanying drawing:

FIG. 1 is a small scale perspective view showing the elements of the present wrench mechanism as they may be arranged for operation on conventional sucker rods. FIG. 2 is a fragmentary plan view taken approximately as indicated by the line 2-2 on FIG. 1. I

'FIG. 3 is a sectional assembly view showing'portions of the impact wrench, output adapter and a torque reactance or anvil member in central longitudinal section (partly as indicated by lines 3x--3x or 3x-3y or 3x--3z on FIG. 2) but with the adapter and anvil mom'-v bers dimensioned for engaging respectively a coupling and sucker rod, instead of the sucker rod and coupling respectively as in FIGS. 1 and 2.

General Arrangement 1 In FIG. 1 the impact wrench SW, adapter A and anvil member M are shown in working position with respect to adjacent sucker rods R and R, the latter rod R having already been lowered into thewell represented in FIG. 1 solely by an end portion of tubing T shown in broken lines. The tubing and rods would be provided with slips orrod clamps (not shown) around the lower sucker-rod R and below its upper upset portion (supporting its square and pin) preparatory to making threaded joint connection with rod R as suspended above, the tubing by a suitable hoist and elevator (not shown), all as well understood in the art.

The impact wrench SW, as shown herewith, has oppositely disposed coaxial output shaft square stubs 10 and. 11 adapted for engagement with complementary sockets in various adapters so that various threaded members of a predetermined magnitude can be engaged by the wrench for tightening or loosening threaded joints. Due to the great lengths of the sucker rods R, R etc. in a typical string, the stubs 10 and 11 cannot operate through adapt ers having coaxial input and output elements either for running in or breakingout of the rods. Therefore the output of the wrench SW in the practice of'the present invention operates through an adapter such as A with offsetinput and output elements, the latter detachably engaging (e.g.) the rod squares S, S, S", FIG. 3, or the coupling wrench flats F, laterally of the longitudinal axis of the wrench stubs. Whichever wrench surface (S or F) is not then engaged by the. adapter'A is enthan that of the rotary impact producing elements of the wrench SW (and with any desired greater mass), to'the end that very little if any manual force will have to be Preferred Impact Wrench The enlarged head portion of impact wrench SW, as shown for example FIGS. 2 and 3 hereof comprises a hollow housing 1 having operatingly integral parallel side plates 2 suitably connected with a hollow handle H which, as suggested in FIG. 2, comprises a metal tube.

The output shaft unit of wrench SW comprises, as shown by comparison of FIGS. 2 and 3, a tool head 3 having a central ratchet toothed portion 3 coaxially thereof between its work engaging square stub portions 10 and 11. An annular inertia member or rotor W surrounds the ratchet toothed portion 3; and bearing bushings 4 rigid with the side plates 2 guide the shaft, handle and the inertia member for angular movement relative to each other about the working axis of the tool head. One or more pawls 5 movably supported on the inertia member W "as in associated recesses 5a therethrough are biased as by springs 50, FIG. 2 only, for engagement with the ratchet teeth. A cam or cams 6, one for each pawl, connected for movement with housing 1 as by being formed on the bushings 4, are operable against the pawls as a function of predetermined angular movement of the handle and inertia member W in a predetermined direction to enable successive escapements and impacts between the pawls and the ratchet teeth.

A coiled compression power spring 7 disposed within the handle H lengthwise thereof operatingly connects the handle to the inertia member W eccentrically thereof as by a crosshead 7 and link 7" so that said predetermined relative angular movement of the handle and inertia member (e.g., angle L, FIG. 2) will, pursuant to said escapements, produce powerful and sharp impacts through energy alternately stored in and released by the spring 7. As will be evident from FIG. 2, clockwise movement of the handle H about the axis of tool head 3 will compress spring 7 axially if the tool head 3 does not move angularly and (assuming three pawls hence three cams 6 and twelve ratchet teeth) escapement and impact occurs for each such angular movement of the handle somewhat more than 30". Operating movement of the handle H can be unidirectional; but with the presently illustrated use of the mechanism by a single operator the handle is moved back and forth in the manner of operating a ratchet wrench. Stops such as shown at 9 and 9' on the rotor W and housing 1 determine the initial or starting position of the inertia member W between impacts. The illustrated square stubs 10 and 11 of tool head '3 usually engage sockets in suitable adapters (not shown) having additional sockets or stubs coaxial therewith and complementary to the work. Stubs 10 and 11 would be operatingly engaged with the work selectively according to whether the fastener is to be loosened or tightened.

Ofiset Adapter Adapter A hereof has input and output socket or equivalent elements (socket 15 and yoke slot 16 as shown) relatively offset from each other a desirably minimum distance such that rotor W of the wrench will adequately clear the work (e.g. coupling C as in FIG. 3) and the body of the adapter is made with sufficient transverse cross sectional area (and/or shape) so as to be substantially rigid. Preferably the wrench SW and adapter A are demountably attached together as by a coupling pin 18 having a threaded head portion 18' engaging threads of a counterbore in the body of the adapter and a nose portion extending into a selected cross hole 19 of the 4 output stubs 10 and 1-1. Thereby, considering the fact that walk or cellar floor surfaces adjacent the well head are usually slippery, the wrench and adapter assembly SWA is safer to use than if its components could easily fall apart.

Slot 16 at the free end of adapter A is shaped and dimensioned fairly snugly to receive the sucker rod squares S, S etc. (as in FIGS. 1 and 2) or the coupling flats F (as in FIG. 3) the sides of the slot having suitably diverging entrance surfaces 16. The arrangement according to FIG. 3 is usually preferred, so that the joint to be made (or broken) is, as at j FIG. 3, at the bottom of the involved coupling which is assumed to be already adequately tight on the rod R as the latter is lowered from the hoist on the derrick or portable service unit boom into joining position. In that way the internal (presumably exposed) threads of the coupling C are not apt to collect dirt during placement of the rod R prior to spinning in of it onto the upstanding threaded pin of previously placed rod R.

For already indicated reasons involving safety of operation it is advisable, before torquing each joint with the mechanism hereof, to detachably secure the wrench and adapted assembly SWA to a suspended element-cg. rod R (FIG. 1) or coupling C (FIG. 3) which is ready to be joined via its screw threads to a mating sucker rod element already in the well. An efficient, i.e. quickly attachable and detachable securing or locking bar arrangement, and which is not subject to sticking in locking position may be made as follows:

The body of the adapter is slotted as at 20 across its end face for receiving and guiding for swinging movement a latch bar 21 pivoted as on a pin 21' intersecting the slot 20 for movement of the bar out of and into its illustrated position across the work receiving slot 16. In looking position the bar 21 can abut the sucker rod element to be operated upon by the impact tool (e.g. one of the wrench flats S as illustrated in FIG. 2 or a peripheral face of a coupling C as in FIG. 3).

The free end of the latch bar 21 has a screw threaded extension 22 and, as shown, a knurled nut 23 having a spheroidal or rounded inner end surface portion 23 is supported by the screw threaded extension 22 and is prevented from complete detachment from the bar 21 as by a headed over portion 22' of the extension. The ballface 23 of captive nut 23 engages a complementary spherical depression .24 on the adapter body coaxial with the extension 22 in the latching position of bar 21. Since the ball and socket faces do not have to be fully seated against each other in order to hold the bar 21 securely in latching position time-wasteful sticking (as by wedging of nut and body faces) is unlikely to occur.

Preferred Anvil Construction; Operation The bifurcated or yoke-like body 25 of anvil assembly or member M has the slot 26 for receiving a coupling C (as in FIG. 1) or for receiving the sucker rod wrench square S" (as in FIG. 3); and the slot 26 is sufliciently deep so that the arms 26' overhand the longitudinal axis of the rod string and tends to balance the mass of the unit M on opposite sides of said axis, i.e., so that the operator does not have to exert much force in holding the anvil in mounted position. Ribs 27 are preferably provided on opposite sides of slot 26 for snug engagement as with the full length of the rod or coupling surfaces (axially of the string), and at the elfective open end of slot 26 the ribs relatively diverge for easy placement of the anvil onto the associated rod element. Handle M of the anvil assembly is preferably a tube although if it is desired to increase the effective mass remotely of the rod string or assembly one way of doing so without material change of proportions would be to use a solid bar in place of such tube.

In breaking out of rods as from a previously operating string the procedure described above is substantially reversed in that the head of the impact wrench SW is inverted whereby the impacts produce (as in FIG. 2) counterclockwise movement of the adapter A about the rod string axis hence unthreading (e.g.) of a coupling in the position C FIG. 3 from the adjacent rod in the well or as at R, FIG. 3. The handles H and M are also relatively reversed horizontally so that the operator can move the wrench handle toward that of the anvil unit in breaking joints. Capping of exposed threads and other conventional steps as well known in oil field practice are of course practiced.

The application and use of impact wrench SW, adapter A and anvil unit M to associated rod string elements superficially resemble application and manipulation 'of an ordinary manually operable sucker rod-wrench and backup wrench outfit. The resemblance is solely in view of the relative motions involved. Actually the operator, with the present system and mechanism, has to maintain only an almost negligible torque on the handle of the anvil or reactance unit M whereas, in the use of bar type rod-wrench equipment the back-up or holding wrench or snipe must have as much torque applied to it as is applied to the main wrench. The manual force which must be applied in the present case to charge or cock the power spring 7 of wrench SW is considerable, but is only a small part of the effective force involved in the powerful impacts delivered by the suddenly released inertia member W via its pawls to the tool head or output shaft -3 of the wrench, hence to the sucker rods or couplings. In making up of a rod string the impacts (e.g., after initial abutment of shoulder faces by spinning in of rods) are counted by the operator in order accurately to predetermine rod pin tension. In brealo ing joints the impacts are simply repeated or accomplished as many times as necessary.

It will be evident in view of the above description (and having in view that the couplings C are short and with negligible torsional flexibility) that the adapter A and reactance anvil M can be designed with operationally identical work-engaging or jaw face portions such as 16 and 27, each [fitting (e.g.) the rod squares S and S", FIG. 3. Since, in effect, coupling C can be considered operatingly integral with rod S as the latter is hung from its usual swivelled support on the derrick or mast, the operations in making up a string of sucker rods would simply ignore the wrench flats on the couplings C. Similarly in breaking out sucker rods from a string (with the jaws engaging the rod squares as just described) it would not be critically import-ant whether the joints were sometimes broken at the top ends of the couplings and at other times at the bottom ends.

I claim:

1. In impact wrenching apparatus for application to thread connected elongated members in a series of string, a manually operated impact wrench unit having a rotary tool head and cooperating mechanism capable of imparting a succession of torsional impacts to the tool head on its rotational axis, a rigid output or extension member connected to turn with the tool head and extending laterally of said rotational axis and having jaw tfaces remotely of said axis for wrenching engagement with one of two thread-connected members, and a rigid anvil member of substantial mass having jaw faces adapted for twist-resisting engagement with the other of such two threadconnected members.

2. Impact wrenching apparatus according to claim .1, wherein the impact wrench unit has a handle extending transversely of the tool head and constituting a force input portion of said mechanism, and the anvil member has a similar handle extending therefrom and disposed :for positional manipulation by one hand of an operator in a plane parallel to the operating plane of the wrench handle while his other hand is in position to work the handle in said plane.

3. In impact wrenching apparatus according to claim 1 wherein one terminal portion of the output or extension member is adapted to be demountably attached to the tool head and an opposite terminal portion of the output member has a locking bar pivotally attached thereto so as to extend in bridging, work-retaining, relation to said first mentioned jaw faces, and a securing device operative detachably to secure a portion of the locking bar remotely of its pivot to the output or extension member.

4. The apparatus according to claim 3 wherein the portion of the locking bar lying remotely of the pivot is a threaded stem, a captive nut threaded on the stem and having a spherical or rounded surface coaxially of the screw thread for detachable engagement with a generally complementary retaining socket surface on the output or extension member.

5. -In impact wrenching mechanism for application to thread-connected elongated members in a series or string, a manually operated impact wrench unit having a rotary tool head, an operating device and a rotary inertia mass element, all three journalled :for angular movement on a common axis, and cooperating impact-producing escapement cam and spring mechanism between said device and mass element and operative to produce torsional impacts on the tool head as a function of angular movement of the operating device in one direction, a rigid output member connected to turn with the tool head and extending laterally of its rotational axis and having jaw tfaces remotely of said axis for wrenching engagement with one of two thread-connected members, and a rigid anvil of substantial mass having jaw faces adapted for twist-resisting engagement with the other of such two thread-connected members.

6. In combination with an impact wrench wherein a rotary tool head is journalled on a handle projecting transversely of the rotational axis of the tool head and wherein a power spring, supported by the handle, reacts thereon and operates through a ratchet and cam-operated escapement mechanism including an inertia member journalled on the handle for angular movement about said tool head axis and connected to the spring in a manner to store and release energy therein and cause impact torque to be delivered to the tool head as a function of relative angular movement of the handle and the inertia member in a predetermined direction; a Wrench member connected to move angularly integrally with the tool head and having manually rigid wrench faces remotely of said axis for wrenching engagement with one of two thread-coupled members, and an anvil member having a massive head portion with mutually rigid wrench faces thereon for twist-resisting engagement with the other of said thread-coupled members, the anvil member having a handle projecting laterally from the head portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,861,728 Vance et a1 June 7, 1932 2,112,693 Douglass Mar. 29, 1938 2,405,757 Rowland Aug. 13, 1946 2,646,966 Lindbeng July 28, 1953 2,688,268 Lear Sept. 7, 1954 2,737,839 Paget Mar. 13, 1956 2,844,982 Swenson July 29, 1958 2,910,901 Ryd Nov. 3, 1959 FOREIGN PATENTS 25 0,7 52 Great Britain Apr. 22., 1926 450,778 Great Britain July 24, 1936 

1. IN IMPACT WRENCHING APPARATUS FOR APPLICATION TO THREAD-CONNECTED ELONGATED MEMBERS IN A SERIES OF STRING, A MANUALLY OPERATED IMPACT WRENCH UNIT HAVING A ROTARY TOOL HEAD AND COOPERATING MECHANISM CAPABLE OF IMPARTING A SUCCESSION OF TORSIONAL IMPACTS TO THE TOOL HEAD ON ITS ROTATIONAL AXIS, A RIGID OUTPUT OF EXTENSION MEMBER CONNECTED TO TURN WITH THE TOOL HEAD AND EXTENDING LATERALLY OF SAID ROTATIONAL AXIS AND HAVING JAW FACES REMOTELY OF SAID AXIS FOR WRENCHING ENGAGEMENT WITH ONE OF TWO THREAD-CONNECTED MEMBERS, AND A RIGID 